Update git submodules

Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Merge "Cleaning up yamllint warnings"
  - Cleaning up yamllint warnings

    yamllint output:
    build/baremetal-environment.yaml
      1:1       warning  missing document start "---"  (document-start)

    build/opnfv-environment.yaml
      6:3       warning  comment not indented like content  (comments-indentation)
      14:4      warning  missing starting space in comment  (comments)
      123:1     warning  comment not indented like content  (comments-indentation)
      128:1     warning  comment not indented like content  (comments-indentation)
      156:1     warning  comment not indented like content  (comments-indentation)

    config/deploy/os-odl-fdio-dvr-ha.yaml
      1:1       warning  missing document start "---"  (document-start)

    config/deploy/os-odl-fdio-dvr-noha.yaml
      1:1       warning  missing document start "---"  (document-start)

    config/network/network_settings_v6.yaml
      225:6     warning  missing starting space in comment  (comments)

    Change-Id: I3985ce0b6740ce4694b5d75b477cb03c3dc49c28
    Signed-off-by: Dan Radez <dradez@redhat.com>